Tube shield and ground strap structure



Jan. 16, 1962 B- JCHNSON 3,017,596

TUBI: SHIELD. AND GROUND STRAP STRUCTURE Filed Aug. 18. 1958 LESTER Edos-msm` 3s 7 ,3 se Joshi United States Patent O M 3,017,596l TUBE SHIELD AND GROUND STRAP STRUCTURE Lester B. Johnson, Des Plaines, Ill., assignor, by mesne assignments, to United-Carr Fastener Corporation,

Boston, Mass., a corporation of Delaware Filed Aug. 18, 1958, Ser. No. 755,794 3 Claims. (Cl. 339-14) This invention relates to a tube socket assembly, and more particularly to an assembly comprising a socket casting having a tube shield -afiixed thereto which is equipped with an integral ground strap yattached to the ground pin of the socket.

It is well known that tube shields are employed for the purpose of dissipating electromagnetic and electrostatic fields developed in the vicinity of a tube by conducting such fields to ground. Thus, the effectiveness of a shield is directly related to the type and quality of the ground connection therefor. One of the difficulties encountered in this respect is that ordinarily tube shields must be releasably secured to the socket casting because the shield necessarily extends to the upper end of the tube, and must then be removed to provide access to the tube for the removal and replacement thereof. Consequently, various grounding devices have been employed for the shields which rely on a mechanical engagement in the nature of a frictional contact with -a limited area thereof. Such frictional interconnections have apparent disadvantages since there is a resistance loss across the limited area thereof, which impedes the grounding function.

An object of the present invention is to provide a tube shield structure which may be permanently aliixed to a socket casting, `and which is equipped with an integral ground strap permanently connected with the ground terminal of the socket casting to establish a good electrical connection therewith. Still another object is that of providing a telescopically adjustable tube shield having a lower end portion permanently secured to a socket casting and providing an integral ground strap mechanically anchored to such casting and soldered or otherwise permanently connected with the center or ground pin of the casting.

Still another object is in the provision of an assembly of the character described, in which the ground strap extends inwardly from the lower end of the shield in juxtaposition with the upper surface of the socket casting so as to be disposed beneath a tube mounted in the casting. Yet 'a further object is in the provision of a structure of the character described, in which the socket casting is adapted for use in conjunction with printed wire boards and has terminals to be pressed therethrough for connection with the printed wires thereof, and in which the socket casting is equipped with a hollow ground pin, into which an end portion of the ground strap depends, for connection thereto in a dip soldering operation. Additional objects and advantages of the invention will become apparent as the specification develops.

An embodiment of the invention is illustrated in the accompanying drawing, in which- FIGURE 1 is a side view in elevation of a socket assembly embodying the invention; FIGURE 2 is a top plan view thereof; and FIGURE 3 is a side view in elevation of the assembly shown in position on a printed wire panel, and in which portions of the structure are shown in section.

The assembly in its entirety is designated with the numeral 10, and comprises a tube shield 11 and a socket casting 12 equipped with a plurality of pin-receiving terminals 13. In the specific illustration, there are n1ne such terminals 13, each of which has an upwardly turned 3,017,596 Patented Jan. 16, 1962 tail or end portion 14 adapted to be inserted through an opening 15 therefor in a printed wire panel 16 equipped along the underside thereof with printed conductors 17. With respect to the casting 12, the terminals 13 thereof and the panel 16, all of these components are substantially conventional and for such reason need not be further described in detail.

The tube shield 11 comprises two telescopically engaged sections 18 and 19, the first of which extends into the latter for free coaxial movement therealong. The upper end of the lower section 18 is turned outwardly as shown at 20 to provide an annular shoulder adapted to abut the inwardly turned lower end portion 21 of the upper section 19. It will be apparent in FIGURE 1 that the upper edges of the outwardly turned end portion 20 have a plurality of inclined surfaces 22 defining cams adapted to be engaged by the lower ends of the cam followers 23 which are defined by inwardly projecting ribs extending axially along the section 19. When the upper section is rotated toward the left as shown in FIGURE 1, the cooperative engagement of the cams 22 and cam followers 23 forces the upper section 19 upwardly with respect to the section 18 to effect a good frictional engagement of the surfaces defined, respectively, by the outwardly extending portion I2() of the lower sect-ion and the inwardly turned portion 21 of the upper section. In the relative position of the sections 18 and 19 shown in FIGURE l, the upper section 19 is free to move downwardly with respect to the section 18 because the c-am followers or ribs 23 are in alignment with the respective channels 24 formed in the upper end portion 20.

The lower shield section 18 at the bottom end thereof has an inwardly turned annular lip 25, that is segmented as shown in FIGURE 2 and is contiguous with the upper surface of the casting 12. Intermediate the segments 25, the shield section 18 is equipped with depending cleats or fingers 26 that extend through slots or recesses 27 provided therefor along the circumferential surface of the flanged upper end 28 of the casting 12. The cleats are turned inwardly as shown at 29 to clamp the lower shield section 18 in position on the casting 12.

One of the lips, which is denoted with the numeral 30 for identification, merges into a ground strap 31 that extends inwardly from the lip along the upper surface of the casting and terminates in an elongated depending tail 32 that extends into the interior of a ground pin or terminal 33 centrally disposed with respect to the casting 12. The pin 33 is adapted to extend through an opening 34 provided therefor in the panel 16 for connection with the ground lead 3'5 of the panel. It will be `apparent from FIGURE 2 that the tail 32 has a greater dimension than the upper portion 31 thereof, and is in substantial abutment with the sides of the ground pin 3-3 throughout its entire length.

Further, the tail 32 is inclined toward one side of the pin 33 so as to abut the same along a portion thereof disposed beneath the panel 16. Thus, in a dip soldering operation wherein the terminals 13 are secured to the conductors 17 therefor, the ground strap is soldered to the ground pin 33 and consequently is electrically connected with the ground conductor 35. Since the ground pin is substantially cylindrical, and the tail 32 of the ground strap generally rectangular and has a width substantially equal to the inner diameter of the pin, the tail of the ground strap may be pressed into the terminal and will maintain the initially established position thereof, whereby a good solder connection between the strap and ground pin is assured.

With the construction described, the tube shield 11 is permanently secured to the casting 12, both by the cleats or fingers 26 and by a rivet 36 which extends through the enlarged portion of the strap in juxtaposition with the socket and which merges into the lip 30. This rivet also enforces a contiguous relation between the strap and upper surface of the socket. Therefore, the ground strap may be soldered to the ground pin 33 to form a permanent connection therewith having excellent electrical characteristics. As a result, the shield is properly grounded and performs an effective shielding function.

While in the foregoing specification an embodiment of the invention has been described in considerable detail for purposes of making a full disclosure thereof, it will be apparent lto those skilled in the art that changes may be made in such details without departing from the principles and spirit of the invention.

I claim:

1. In combination with a casting equipped with a hollow ground terminal and adapted for use with a printed wire panel, a tube shield member secured to said casting, a ground strap formed integrally with said shield, said ground strap extending inwardly from said shield along the upper surface of said casting and having a depending tail extending into theinterior of said ground terminal, said tail being substantially of the same width as the inner diameter of said ground terminal and angularly disposed relative to the longitudinal axis thereof to provide a portion adjacent its lower end in contiguous relation to said ground terminal.

2. In combination, a socket casting equipped adjacent the upper end -thereof with an outwardly extending flange provided with spaced notches, and a telescoping tube shield provided at the lower end thereof with a plurality of cleats respectively seated in said notches and turned under said flange to anchor said shield to said casting, said casting having a centrally disposed ground terminal extending downwardly therethrough and provided with a hollow interior, said shield at the lower end thereof being equipped with an inwardly turned lip terminating in a ground strap lying along the upper surface of said casting, said ground strap being provided with a depending tail extending into the interior of said hollow ground terminal and into substantial abutment with a wall portion thereof to provide a solder connection therewith in a dip soldering operation subsequent to the mounting of the casting on a printed wire panel.

3. The combination of claim 2 in which said tail has a transverse dimension such that it is in substantial engagement throughout the length thereof with said ground terminal, and in which rivet means are provided to permanently anchor said ground strap to said casting along the upper surface thereof.

References Cited in the le of this patent UNITED STATES PATENTS 

